Add DVM Function: APPEND_SC_CODE

[lcances]

Description

Add a DVM function to append code to an already existing smart contract (without erasing old code). The function is called APPEND_SC_CODE and aim to solve the following problem:

As TX parameter consume gasStorage, and Store also consume gasStorage UPDATE_SC_CODE is limited to 10k characters. That mean if your new code is bigger than 10k, you cannot update your SC. (unless you want to remove features)

The new function will allow for the following:

• Updating the SC without deleting old code
• Release bug fixes by rewriting function implementation
• Allow to reach the 20k limit without installing a brand new SC (very interesting in order to keep SC data)
• Change the SC from Mutable to Immutable
• Split your SC into multiple code, enabling a "migration" approaches to SC implementation

Fixes # (issue)

Type of change

Please select the right one.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] This change requires a documentation update
• [ ] This will require a HardFork to be enabled

Which part is impacted ?

• [ ] Wallet
• [x] Daemon
• [ ] Miner
• [ ] Explorer
• [x] Simulator
• [ ] Misc (documentation, comments, text...)
• [x] DVM

Checklist:

• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] My changes generate no new warnings

License

Im am contributing & releasing the code under DERO Research License (which can be found here).

[lcances]

Well I am closing this PR because I have a better understanding of the whole situation.

I will soon propose two different approaches. One specific for the UPDATE_SC_CODE in particular, another one a bit more general.

See you soon